arXiv subjects

Adriana Errico

Publications and source records attributed to Adriana Errico.

4 recordsLinked to original sources

arXiv2026

HD 38973 b -- a cold Saturn orbiting a Sun-like star

We report the detection of a long-period companion to the nearby solar-type star HD\,38973 using precision radial-velocity measurements. The radial-velocity data reveal a coherent Keplerian signal with a period of $\sim$3000~days and moderate eccentricity, yielding a minimum mass in the sub-Jovian regime. We complement the radial-velocity analysis with astrometric constraints from the \emph{Hipparcos--Gaia} Catalog of Accelerations (HGCA). Although no significant proper-motion anomaly is detected for HD\,38973, the absence of an astrometric signal provides an informative upper limit on the companion mass. By combining the radial-velocity posterior with the HGCA likelihood, we rule out high-mass solutions at low inclinations and derive a robust upper bound on the true companion mass. We find the best-fitting true mass to be $0.240_{-0.040}^{+0.102}\,M_{\rm Jup}$, on an orbit with period $2733^{+210}_{-190}$ days, making HD\,38973b a likely cold Saturn. This study highlights the diagnostic power of astrometric non-detections when combined with precision radial velocities, demonstrating that meaningful constraints on companion masses can be obtained even in the absence of a detected astrometric signal.

astro-ph.SR↗

arXiv2026

Hot Jupiter - Cold Jupiter: A complex sibling relation

A handful of planetary systems hosting a Hot Jupiter have been subsequently found to also host long-period giant planets. These ``cold Jupiters,'' giant planets residing beyond the snow line ($\sim$3\,au), play an important role in the dynamical evolution of the system as a whole. In this work, we investigate the detectability of cold Jupiters around a sample of 28 well-studied Hot Jupiter host stars to estimate the occurrence rate of this distinctive system architecture. We perform extensive simulations using the combination of all publicly available radial velocity (RV) data for those stars with synthetic RV data. The synthetic data test observing strategies along three axes: cadence, duration, and measurement precision. For each scenario, we determine detection limits based on the semi-major axis at which a 1 Jupiter mass planet would be recovered 50\% of the time. We find the following: 1) the existing RV data are remarkably insensitive to these Hot Jupiter/Cold Jupiter pairs; 2) the total baseline over which an observational campaign is carried out is the dominant factor in our ability to detect cold Jupiters; and 3) the results are relatively insensitive to the individual RV measurement precision. We conclude that metre-class telescopes with lower RV precision are ideally suited to surveying Hot Jupiter-cold Jupiter systems.

astro-ph.EP↗

arXiv2025

Optimising Radial Velocity Detection Limits for Southern Habitable Worlds Observatory Targets

The planned NASA Habitable Worlds Observatory (HWO) flagship mission aims to image and spectroscopically characterise 25 Earth-size planets in the habitable zones of their stars. However, one giant planet in the habitable zone can ruin your whole day. Recent work has examined the current state of our knowledge on the presence or absence of such objects in samples of likely HWO targets, and that knowledge has been found wanting; even Saturn-mass planets remain undetectable in many of these systems. In this work, we present simulations assessing the degree to which new campaigns of high-cadence radial velocity observations can ameliorate this woeful state of affairs. In particular, we highlight the value of moderate-precision but highly flexibly-scheduled RV facilities in aiding this necessary HWO precursor science. We find that for a subset of Southern HWO stars, 6 years of new RVs from the Minerva-Australis telescope array in Australia can improve the median detection sensitivity in the habitable zones of 13 likely HWO targets to $\sim$50 Earth masses, an improvement of $\sim$44%.

astro-ph.EP↗

arXiv2022

HD 83443c: A highly eccentric giant planet on a 22-year orbit

We report the discovery of a highly eccentric long-period Jovian planet orbiting the hot-Jupiter host HD\,83443. By combining radial velocity data from four instruments (AAT/UCLES, Keck/HIRES, HARPS, Minerva-Australis) spanning more than two decades, we find evidence for a planet with m~sin~$i=1.35^{+0.07}_{-0.06}$\,\mj, moving on an orbit with $a=8.0\pm$0.8\,au and eccentricity $e=0.76\pm$0.05. We combine our radial velocity analysis with \textit{Gaia} eDR3 /\textit{Hipparcos} proper motion anomalies and derive a dynamical mass of $1.5^{+0.5}_{-0.2} M_{\rm Jup}$. We perform a detailed dynamical simulation that reveals locations of stability within the system that may harbor additional planets, including stable regions within the habitable zone of the host star. HD\,83443 is a rare example of a system hosting a hot Jupiter and an exterior planetary companion. The high eccentricity of HD\,83443c suggests that a scattering event may have sent the hot Jupiter to its close orbit while leaving the outer planet on a wide and eccentric path.

astro-ph.EP↗